Error correction coding techniques have been commonly used to reduce errors introduced during digital data transmission or storage. Prior to transmission, for example, each piece of data, such as a 16 bit word, may be encoded to incorporate additional information so that upon reception, the data may be recovered even when errors are introduced during transit between transmitter and receiver.
In 1962, Robert Gallager disclosed an error correction coding technique called low-density parity-check (LDPC) codes. LDPC codes are linear binary block codes whose codewords satisfy a set of M linear parity-check constraints. LDPC codes were largely forgotten after their initial disclosure due to lack of computing power, but were revived in the mid 1990's and have since been recognized to offer better performance and less decoding complexity than many later disclosed error correcting codes.